1. Field of the Invention
The present invention relates to the art of copying and printing machines, and more particularly, to a paper sheet receptacle for receiving paper sheets discharged from a printing portion of a copying or printing machine in a stacked up state.
2. Description of the Prior Art
A copying or printing machine is generally provided with a paper sheet receptacle having a barrier wall means adapted to be collided at with a front edge of a paper sheet flying as discharged from a printing portion of a copying or printing machine with the front edge as a forward end, and a stack floor means adapted to receive the paper sheet collided at and falling along the barrier wall means from below thereof, so that, when a plurality of paper sheets are successively discharged, they are successively stacked up in the paper sheet receptacle to form a stacked up body of the paper sheets.
According to the recent development of copying and printing machines for higher speed operation, the paper sheets discharged from the printing portion of those machines fly at high speed toward the paper sheet receptacle with each one edge thereof posing a forward end, colliding at the barrier wall means of the paper sheet receptacle with a large momentum. In this case, if the barrier wall means has a rigid construction, a large collide sound is generated, and further the paper sheet is sprung back for a large distance by the reaction applied by the barrier wall means. Since the spring-back distance is much affected even by a small difference in the flying posture of each paper sheet as magnified by a corresponding difference of air resistance, the stacked up body of the paper sheets formed in the paper sheet receptacle shows a great disorder with scattered distances left between the front edges of the paper sheets and the wall surface of the barrier wall means.
Against such a problem the conventional counter-measure is to attach a cushion sheet means made of sponge, rubber, or the like onto the surface of the barrier wall means where the front edges of the paper sheets collide. Such a cushion sheet attached onto the front surface of the barrier wall means lowers the collide sounds of the paper sheets to certain extent when the cushion sheet is constructed with a soft material having a low modulus of elasticity. However, when the cushion sheet is made so soft as a sufficient muffling effect is available, the positioning function of the barrier wall means against the front edges of the paper sheets lowers, so that the disorder of the paper sheets stacked up in the paper sheet receptacle increases.